1. Field of the Invention
The present invention relates to electric-powered model vehicles, such as model trains, and more particularly, to an adaptive drive mechanism for a model train or other model vehicle.
2. Description of Related Art
Various model trains and vehicles are known in the art, which model an actual or imaginary train or vehicle at a reduced scale. In a typical model layout, a model train having an engine is provided. The model train engine includes an electrical motor that receives power from a voltage that is applied to model railway tracks. A transformer is used to apply the power to the tracks, while contacts (e.g., a roller) on the bottom of the train, or metallic wheels of the train, pick up the applied power for the train motor. In some model train layouts, the transformer controls the amplitude, and in a DC system, the polarity, of the voltage, thereby controlling the speed and direction of the train. In HO systems, the voltage is a DC voltage. In O-gauge systems, the track voltage is an AC voltage transformed by the transformer from a household line voltage provided by a standard wall socket, such 120 or 240 V, to a reduced AC voltage, such as 0-18 volts AC.
Model electric trains therefore include a drive train linking one or more pairs of powered drive wheels to an electric motor housed in a model locomotive. Many model locomotives make use of a direct gear drive, such as a spur gear set or other gear drive. Direct gear drives provide a direct mechanical link between the motor and the drive wheels, and are generally recognized as providing excellent responsiveness and low backlash for speed control and motion reversal. Properly designed gear drives are also reliable, have low maintenance requirements, and long service lives. These characteristics make gear drives prevalent in many model vehicles.
Notwithstanding their advantages, gear drive mechanisms may be subject to certain disadvantages. Conventional gear drives are used with a relatively rigid or stiff mechanical connection between the drive wheels and the motor. Consequently, displacement of the drive wheels from bumps or unevenness of a model track is transmitted to the model locomotive, which may visibly bounce up and down or sway side-to-side in a way that does not resemble a full-scale locomotive. Modern full-scale locomotives employ sophisticated drive trains and suspension systems, as well as being much more massive than reduced-scale model locomotives. Full-scale model locomotives therefore may exhibit a much smoother, stable response to vibration received from travel over the track bed, as compared to many prior-art model vehicles. Achieving a more realistic dynamic response in model vehicles is desirable, but only within certain economic constraints. For example, merely scaling down all the primary mechanical characteristics of actual locomotives, such as mass, moment of inertia, suspension and drive systems, is not economically feasible for model vehicles intended for consumer toy or hobbyist applications.
Accordingly, a need exists for a model train with a drive mechanism that overcomes these and other limitations of the prior art.